全文获取类型
收费全文 | 4978篇 |
免费 | 71篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 62篇 |
综合类 | 5篇 |
化学工业 | 968篇 |
金属工艺 | 77篇 |
机械仪表 | 105篇 |
建筑科学 | 210篇 |
矿业工程 | 27篇 |
能源动力 | 105篇 |
轻工业 | 379篇 |
水利工程 | 66篇 |
石油天然气 | 15篇 |
无线电 | 276篇 |
一般工业技术 | 608篇 |
冶金工业 | 1595篇 |
原子能技术 | 47篇 |
自动化技术 | 508篇 |
出版年
2019年 | 30篇 |
2018年 | 38篇 |
2016年 | 38篇 |
2015年 | 31篇 |
2014年 | 77篇 |
2013年 | 300篇 |
2012年 | 126篇 |
2011年 | 162篇 |
2010年 | 96篇 |
2009年 | 109篇 |
2008年 | 144篇 |
2007年 | 152篇 |
2006年 | 134篇 |
2005年 | 155篇 |
2004年 | 127篇 |
2003年 | 130篇 |
2002年 | 135篇 |
2001年 | 75篇 |
2000年 | 82篇 |
1999年 | 72篇 |
1998年 | 97篇 |
1997年 | 90篇 |
1996年 | 82篇 |
1995年 | 94篇 |
1994年 | 66篇 |
1993年 | 105篇 |
1992年 | 94篇 |
1991年 | 50篇 |
1990年 | 97篇 |
1989年 | 83篇 |
1988年 | 85篇 |
1987年 | 92篇 |
1986年 | 78篇 |
1985年 | 112篇 |
1984年 | 116篇 |
1983年 | 101篇 |
1982年 | 100篇 |
1981年 | 88篇 |
1980年 | 60篇 |
1979年 | 107篇 |
1978年 | 75篇 |
1977年 | 104篇 |
1976年 | 82篇 |
1975年 | 103篇 |
1974年 | 67篇 |
1973年 | 82篇 |
1972年 | 48篇 |
1971年 | 38篇 |
1970年 | 35篇 |
1969年 | 34篇 |
排序方式: 共有5053条查询结果,搜索用时 15 毫秒
21.
22.
Melamed Barbara G.; Matthews Karen A.; Routh Donald K.; Stabler Brian 《Canadian Metallurgical Quarterly》1986,5(3):181
This article introduces the current issue of Health Psychology. The call for early intervention to prevent adulthood health problems and the need to consider each period of children's lives within its developmental perspective are the main emphases in this special issue of the journal. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
23.
Deborah C. Blaine John D. Gurosik Seong Jin Park Randall M. German Donald F. Heaney 《Metallurgical and Materials Transactions A》2006,37(3):715-720
Sintering experiments with various molybdenum powders are rationalized using a master sintering curve concept that collapses
density, grain size, or other parameters onto a single curve. In this case, the integral work of sintering is developed and
customized for different green densities. Construction of the master sintering curve is described to show how the curve can
be normalized with respect to green density effects. Various grades of molybdenum for metal injection molding and die compaction
are included in the analysis, processed over a range of heating cycles. Die-compacted samples of varying green densities are
used to illustrate the efficacy of the new, normalized master sintering curve concept. Sintering cycle optimization is one
possible outcome from this analysis. 相似文献
24.
25.
This meta-analysis examines the influence of electronic communication media on group idea generation tasks. Data from the following three areas of the brainstorming literature are synthesized to assess differences across performance variables and group member satisfaction: (1) electronic brainstorming (EBS) groups versus traditional face-to-face (FTF) interacting groups, (2) EBS groups versus nominal groups, and (3) EBS versus electronic nominal (e-nominal) groups. The results of this integration show that EBS groups are more productive and more satisfied with the interaction process than FTF groups. Additionally, large EBS groups outperformed nominal groups, whereas small nominal groups outperformed EBS groups. These findings have important implications for electronic collaboration and teamwork in both academic and organizational settings, especially given the recent proliferation of virtual teamwork. 相似文献
26.
Pareto multi-criteria decision making 总被引:1,自引:0,他引:1
The paper concerns design governed by multiple objective criteria, which are conflicting in the sense of competing for common resources to achieve variously different performance objectives (financial, functional, environmental, esthetical, etc.). A multi-criteria decision making (MCDM) strategy is proposed that employs a tradeoff-analysis technique to identify compromise designs for which the competing criteria are mutually satisfied in a Pareto-optimal sense. The MCDM strategy is initially developed for the case of design governed by n = 2 objective criteria. It is then extended to design governed by n > 2 objective criteria, by introducing the concept of primary and aggregate criteria. It is proved that, from among the theoretically infinite number of feasible designs forming the Pareto front for a design problem governed by n independent objective criteria, there exists a unique Pareto-compromise design that represents a mutually agreeable tradeoff between all n criteria. This remarkable result is illustrated for a flexural plate design governed by n = 2 criteria, a bridge maintenance-intervention protocol design governed by n = 3 criteria, and a media centre envelop design governed by n = 11 criteria. 相似文献
27.
Blanchard Kimberly A.; Morgenstern Jon; Morgan Thomas J.; Lobouvie Erich W.; Bux Donald A. 《Canadian Metallurgical Quarterly》2003,17(4):328
Negative consequences are an important component of the substance use change process, yet no standardized measure exists to assess consequences of use. This study evaluated the psychometric properties of the Inventory of Drug Use Consequences, a self-report measure assessing drinking and drug use consequences. Participants (N=252) were assessed at entry into outpatient substance abuse treatment. Items loaded strongly on 1 factor, and internal consistency of the total scale was high. Fifteen items with the highest correlations with the total scale were chosen to represent the construct. The shortened measure exhibited good internal consistency, convergent and discriminant validity, and detected change over time and may be the measure of substance use consequences that is lacking in the field. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
28.
Capital cost correlations are given for oil-water separators, equalization basins, primary clarifiers, clarifiers and clarifier mechanisms, reverse osmosis unit, ultrafiltration units, gravity filters and miroscreens. Data are included for raw sewage, intermediate and recirculation pumping stations and for preliminary treatment (or bar screens, grit removal, overflow and bypass chamber and Parshall flume), for grit removal, comminution and gas stripping. The correlations are accurate to ± 30%, expressed in Canadian dollars and adjusted to a Marshall and Swift value of 1000. Details as to what components are included in the cost are given. Data are given for the labour and material costs to create a working process module. For inflation indices, a critique of the Engineering News Record, EPA small city, Marshall and Swift, Chemical Engineering and Southam inflation indices suggested that the Marshall and Swift index is most appropriate for the construction and process equipment studied here. Concerning the currency exchange, for the equipment and processes in this study, equipment costs the same whether expressed directly in US or Canadian dollars. To put the current data into perspective, several hundred sources of cost data were analyzed. The major correlations are compared, on a consistent basis, with current data. 相似文献
29.
In this article, an analysis is given of Lockhart v. McCree, a recent decision in which the Supreme Court held it was not unconstitutional in cases in which the prosecution was requesting capital punishment to exclude from trial jurors during the guilt phase of the prosecution those jurors who have moral or religious scruples against imposing the death penalty. At issue in the case was the scientific soundness of three decades of social science research that indicated that the absence of jurors with such scruples created a jury that was pro-prosecution and, therefore, conviction-prone. The ways in which those data were scrutinized by both the majority and the dissent in Lockhart are described. The case is used as an example of the use of social science data in constitutional decision making and of the need to conduct methodologically rigorous, highly relevant research if psychologists are to genuinely influence judicial opinion on controversial issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
30.
F. Javier Lerch Deborah J. Ballou Donald E. Harter 《Annals of Software Engineering》1997,3(1):345-366
We describe the use of simulation‐based experiments to assess the computer support needs of automation supervisors in the United States Postal Service (USPS). Because of the high cost of the proposed system, the inability of supervisors to articulate their computer support needs, and the infeasibility of direct experimentation in the actual work environment, we used a simulation to study end‐user decision making, and to experiment with alternative computer support capabilities. In Phase One we investigated differences between expert and novice information search and decision strategies in the existing work environment. In Phase Two, we tested the impact of computer support features on performance. The empirical results of the two experiments showed how to differentially support experts and novices, and the effectiveness of proposed information systems before they were built. The paper concludes by examining the implications of the project for the software requirements engineering community. 相似文献